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Design and Optimization of a 4 Tesla 200 mm Aperture Helium-Free Nb-Ti Nested CCT Quadrupole/Dipole Superconducting Magnet
No full textThis paper presents the design and optimization of a low-weight helium-free Nb-Ti CCT superconducting magnet (MAGDEM – MAGent DEMonstrator) for the R&D; phase of the ISOLDE Superconducting Recoil Separator (ISRS) at CERN (Geneva, Switzerland). The system can be expanded to other accelerator applications demanding compact lightweight superconducting magnets, such as medical hadron therapy systems. The innovative design incorporates a dipole coil within a quadrupole coil, enhancing field integrals and operational efficiency within its concise 590 mm length. This configuration effectively achieves a 36-degree maximum bend of the particle beam, with a concentrated effort on minimizing field errors on a tightly curved path to below one unit at a peak field of nearly 4 Tesla. Additionally, the magnet includes a slightly tapered design in its straight tubes, which aids in two key areas: simplifying the assembly of the tube sets and enabling the application of radial pre-stress to the assembly. Operating at approximately 100 A, The MAGDEM design is tailored to efficiently reduce heat leakage, allowing for a single cryocooler to maintain 4.5 K. The particle storage ring of the ISRS spectrometer will incorporate a set of MAGDEM units to guide and bend the trajectory of radioactive beams using a Fixed Field Alternating Gradient (FFAG) configuration. The paper emphasizes the novel design elements, such as the tightly curved field error optimization in a straight yet tapered coil set of formers
Best practices: the theoretical and practical underpinnings of writing code that is less bad
No full textAbstract
Software development is a tricky job; best practices help. This lecture explains why, and suggests some ingredients people at CERN have found useful over the last decades. Together they can reduce bugs, improve code usability and maintenance; in short: they simply help you write better code.
Bio
Axel started off as a physicists, then took the exit into the land of computing by joining the ROOT team. He is representing CERN and its users at the ISO C++ committee. Axel has given numerous presentations, workshops and tutorials, for instance lectures to students, at the CCC/33C3 and ACCU conference and a Google Tech Talk.
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Searches for Higgs coupling to charm quarks at the ATLAS experiment
No full textThis talk presents ATLAS measurements of the Higgs coupling to charm quarks. Two different approaches are taken into account: direct measurement through the VH(cc) channel and indirect search from the H+c production cross-section
The PUMA offline ion source beamline
No full textThe antiProton Unstable Matter Annihilation experiment (PUMA) at CERN aims to study the nucleonic composition in the matter density tail of stable and radioactive nuclei using low-energy antiprotons. Since there is no facility in which both low-energy antiprotons and radioactive nuclei can be produced, the experimental realization with exotic nuclei requires the transportation of the antiprotons from the Extra Low ENergy Antiproton (ELENA) facility to the nearby located Isotope mass Separator On-Line DEvice (ISOLDE). For tests and first applications of the proposed experimental technique to stable isotopes at ELENA, a dedicated offline ion source beamline was developed that will provide isotopically pure, cooled and bunched ion beams with intensities of more than 104 ions per bunch while maintaining a vacuum of better than 5×10-10mbar at the handover point. This offline ion source beamline is characterized and its capabilities are demonstrated using the example of stable krypton isotopes.The antiProton Unstable Matter Annihilation experiment (PUMA) at CERN aims to study the nucleonic composition in the matter density tail of stable and radioactive nuclei using low-energy antiprotons. Since there is no facility in which both low-energy antiprotons and radioactive nuclei can be produced, the experimental realization with exotic nuclei requires the transportation of the antiprotons from the Extra Low ENergy Antiproton (ELENA) facility to the nearby located Isotope mass Separator On-Line DEvice (ISOLDE). For tests and first applications of the proposed experimental technique to stable isotopes at ELENA, a dedicated offline ion source beamline was developed that will provide isotopically pure, cooled and bunched ion beams with intensities of more than ions per bunch while maintaining a vacuum of better than mbar at the handover point. This offline ion source beamline is characterized and its capabilities are demonstrated using the example of stable krypton isotopes
LHC Triggers using FPGA Image Recognition
No full textThe implementation of convolutional neural networks in programmable logic, for applications in fast online event selection at hadron colliders is studied. In particular, an approach based on full event images for classification is studied, including hardware-aware optimisation of the network architecture, and evaluation of physics performance using simulated data. A range of network models are identified that can be implemented within resources of current FPGAs, as well as the stringent latency requirements of HL-LHC trigger systems. A candidate model that can be implemented in the CMS L1 trigger for HL-LHC was shown to be capable of excellent signal/background discrimination, although the performance depends strongly on the degree of pile-up mitigation possible prior to image generation
ATLAS Level-1 Trigger Menu Testing
No full textThe ATLAS experiment, located at the LHC at CERN, requires a flexible and comprehensive Level-1 Trigger configuration to meet its diverse scientific goals. A robust framework, presented in this contribution, validates such a configuration throughout every year of data-taking. The Level-1 Central Trigger system is built with software-programmable custom hardware and issues the trigger decision depending on this configuration. Testing involves simulation and a hardware replica of the system itself. With the advanced monitoring capabilities of the system, we check that any input signal in the CTP will produce the expected trigger items in the expected time frame, and with the expected trigger information (in both hardware and simulation). This presentation covers testing methods and challenges due to the ATLAS detector's complexity and introduces a new user interface for the testing framework
The ATLAS Run-3 Trigger Menu
No full textThe ATLAS experiment in the LHC Run 3 is recording up to 3 kHz of fully-built physics collision events out of an LHC bunch crossing rate of up to 40 MHz, with additional rate dedicated to partial readout. A two-level trigger system selects events of interest to to cover a wide variety of physics while rejecting a high rate of background events. The selection of events targets both generic physics signatures, such as high pT leptons, jets, missing energy, as well as more specific signatures targeting specific physics, such as long lived particles, or di-Higgs events. We will present an overview of the ATLAS trigger menu system highlighting the new developments and changes for run 3. We will also highlight some of the performance improvements in run 3
EFT strings and dualities in 4d
No full textWe investigate the global structure of the states becoming light at perturbative limits of 4d string and M-theory compactifications, identifying the different duality frames that emerge asymptotically and how they fit together in moduli space. These limits are characterized by the presence of EFT strings - a special class of axionic BPS strings whose tension, derived from the IR Kähler potential, vanishes in Planck units at infinite field distance. An intriguing integer scaling relation, with in Planck units, connects the tension of these strings to the mass scale of the leading tower of states along the string flow. We show that this relation also holds for the subleading towers below the species scale that generate the tower convex hull, implying that their associated vectors lie in a lattice generated by those of the EFT strings. This reveals a striking UV/IR interplay and offers organizing principles for the parametric hierarchies among the relevant UV scales in a given perturbative limit and the web of dualities governing 4d string vacua
Influence of Crystal Fiber Inhomogeneity on the Energy Resolution of a Sampling Electromagnetic Calorimeter
No full textSampling electromagnetic calorimeters (ECALs) are widely used in high-energy physics (HEP) experiments, thanks to their ability to efficiently measure electromagnetic particles’ energy over a broad dynamic range while maintaining good energy resolution. These detectors alternate passive layers made of dense absorber materials, with active layers, such as scintillators. Scintillating materials, such as inorganic garnets, are promising candidates for high-luminosity environments such as the Large Hadron Collider (LHC) due to their high radiation hardness, ensuring longer operational lifetimes without compromising performance. However, fluctuations in light yield (LY) can lead to a degradation in energy resolution ( ER ). One concept of sampling calorimeter is the so-called spaghetti calorimeter (SpaCaL); it relies on optimal scintillating fiber placement inserted in the heavy absorber. Hence, addressing possible LY variations is critical to guarantee that the detector meets the stringent requirements of future high-luminosity runs at the LHC. To maintain optimal ECAL performance, providing feedback to scintillator producers on the acceptable limits of LY variation is essential. For this purpose, a tungsten for the absorber and GAGG for the scintillating material of the sampling electromagnetic calorimeter (W-GAGG) SpaCal was modeled using Monte Carlo (MC) methods. Electrons with energies ranging from 1 to 100 GeV were simulated through the SpaCal to study ER . We introduced artificial longitudinal variations of LY along the GAGG fibers with fixed values across a range of conditions to evaluate their impact on our modeled detector’s performance. Our results indicate that to preserve ER and maintain an acceptable constant term c=1% , the longitudinal variation of LY should not exceed 2%/cm. In addition, we found the optimal fiber configuration to minimize performance degradation from LY fluctuations by testing different end orientations and placements relative to the reflector in both SpaCal sections